Develop a portable, microcomputer controlled scanning digitizer and auxilliary devices to measure: (1) X-ray target intensity distributions directly; (2) light intensity distributions from fluorescent screens, image intensifiers, and backlighted, developed x-ray films; and (3) kilovoltage, x-ray exposure, half- value layers, and time of exposure. Develop software to: (1) calculate and display in 3-D graphics, Optical Transfer Functions and Modulation Transfer Functions from measured Point Spread Functions; (2) characterize and calculate x-ray parameters and predict x-ray image parameters; and (3) educational software explaining the physical basis of x-ray image theory. The portable system will enable the imaging characteristics of an x-ray system to be measured rapidly in situ in the field at a sophistication level found now only at advanced laboratory facilities and requiring substantial time. The increased knowledge of image parameters should improve the level of medical image quality and reduce patient radiation dose. The developed system will performed x-ray unit measurements now requiring several instruments and it will use recent solid-state advancements in microcomputer hardware. It has significant potential non x-ray image systems because of its portability, ease of use, multifunction capability, and major cost savings compared to other instruments and methods.